A chlorate (or perchlorate) candle is a chemical device used to store and produce gaseous oxygen. It is both weight and volume efficient, when compared to conventional pressurized oxygen storage. A candle usually consists of a mixture of granular sodium chlorate (or may alternatively contain lithium chlorate, sodium perchlorate,or lithium perchlorate), iron particles, fiberglass binder and other trace chemicals (used for controlling oxygen gas impurities) that is pressed or cast into a cylinder (or other cross sectional form), resembling a wax candle. When the end of a candle is ignited (either by a resistance wire, chemical ignition "cap" or other means) the sodium chlorate decomposes exothermally producing oxygen. The temperature required to sustain decomposition of the candle is supplied by oxidation of the iron. Candles were developed during the Second World War and are in widespread use today for purposes ranging from emergency oxygen generation on commercial airliners to producing welding gas. Candles release about thirty-five to forty-five percent of their weight as oxygen, depending on the chemical used. Sodium chlorate provides the lowest performance, but is easiest to implement. Candles based on other chemicals are currently only developmental.
In most applications such as aircraft emergency breathing and welding gas supply, candles are packaged and discharged individually. An oxygen generator for an unmanned undersea vehicle (UUV) energy system, however, will require a number of candles that are discharged sequentially or in combination to meet anticipated UUV power consumption profiles. Development of a practical oxygen generator requires optimizing the arrangement of candles in a single pressure vessel, to minimize weight and volume of the system. Dense packaging of the candles is desirable but adequate thermal insulation of each candle is required to prevent a burning candle from igniting an adjacent candle. Additionally, the candles must be supported to prevent movement and breakage. Although there are few examples of multi-candle oxygen generators (MCOG's), those that have been made rely on a free-standing structure resembling a wine rack into which candles can be inserted. The pressure vessel surrounds the wine rack and candle assembly.
A primary disadvantage of this method is that it requires a separate structure to support the candles, which increases the weight and volume of the oxygen generator. This structure also must support the thermal insulation surrounding each candle.
This invention features a separator plate for a chemical oxygen generator candle including an elongate rigid thermal insulating section and at least a first conduit section on one side of the rigid section having a multiplicity of gas flow paths for conducting released oxygen from a burning candle longitudinally along the plate for increasing the burning action of the burning portion of the candle and preheating the unburned portion of the candle and for retaining gas to act as a thermal insulator when the candle is not burning.
In a preferred embodiment there is a second conduit section on the other side of the rigid section opposite the first conduit section. The plate may be generally planar and the surface of the first conduit section facing the candle may be curved or conformed to whatever shape the candle may have. The second conduit section may also be curved or conform to whatever shape the candle may have.